Better is all relative. Each has pro's and con's. Its all what you are willing to spend, maintain, and personal preference.

Consider the possibility that you get a crappy pump (5-10% will crash within the first year statistically). With dual pumps on separate systems if one crashes it only over heats its section without the pump working, so you risk the CPU or the GPU but not both.

This will come at some cost tho.

Extra funding needed for all the extra pieces for both loops.

You will have to maintain 2 loops instead of just 1. Bleeding each one individually, draining and refilling individually at some points to keep things fresh.

Its all really what you are willing to do. As far as temps go, if done right a single loop will stay just as cool as 2 separate ones. It all boils down to you.

Its got a decent audible note, but not really that bad. If its THAT LOUD you may consider RMA'ing it as it may be faulty. I have 2 fountain pumps outside that don't even compare, they are much louder. My old GTX250 GPU during gaming mode at 100% fan speed over shadows the sound and I have to be on top of it at 50% to be able to hear it over the regular fans in the case.

Mine runs at 12v and stays around 3550 rpms consistently. I think its just about right personally. I can hear it so I know its working so I don't fret about the CPU cooking, but its no worse than the rest of the PC and with the speakers at a decent volume, I can't hear any of it anyways.